a 10kg rock is raised to a height of 100m. what is the velocity of the rock at 80m?

Question

its conceptual physics please help me!!!!!!!!!!!!!!!!!!!

Answer 1

Raised to 100m and then dropped, right?

it falls for "t" seconds as in s = 1/2 a t^2 (s = distance, a = acceleration of gravity)
s=80m a = 9.80m/s^2 so it works out like this:

80 = 9.8/2 * t ^ 2 (t squared)

solve for t
t = 4.0406 seconds

Now the rock accelerates at 9.8m/sec for every second it falls,
so the velocity = 9.8 * 4.0406 = 39.6 meters/second at 80meters

Answer 2

Use the equation V^2 - U^2 = 2 a S.

U = 0
V =?
a = 9.8 m/s^2.
S = 20 m. (Since the rock is dropped from 100m , at 80m the rock has traveled 20m)

V^2 = 2 x 9.8 x 20 = 392

V = 19.8m/s

Answer 3

This is a kinematics problem.

You can use the equation.

vxf^2 = vxi^2 + 2ax(xf-xi)

xf = final position = 0
xi = initial position = 20
vxi = intitial velocity = 0
vxf = final velocity
ax = gravity = g = -9.8


Therefore,

vxf^2 = 0 + 2(-9.8)(-20)
vxf^2 = 392
vxf = (392)^1/2
vxf = 19.79 meters/second

The mass of the object in this problem doesn't matter, all objects of sufficient mass fall at the same acceleration. Which in this case, the acceleration is equal to gravity. It does not matter that the object is off the ground 100 meters, it only fell 20, so that is what you need to calculate. The mass and extra height of the object are put into the problem to throw you off.

Hope this helps.

Answer 4

first of all, the weight has no bearance on the rocks terminal velocity. the answer varies, based on if you mean 80m up (fell 20m) or 80m down (20m away from the ground). If it has only fallen 20m, the answer is 155 fp/s. if it has fallen 80m, the answer is 382 fp/s. the true answer will vary based on where on earth you drop the rock (magnetic fields slightly distort gravity towards the equator), and the surface area of the rock (wind resistance). hope this help u! btw, the terminal velocity would be @ 468 fp/s, having fallen 102.6m

Answer 5

When initial velocity is 0,

V^2= 2*a*delta Y

Delta y = 80,
therefore, V^2=2*9.8*80
v^2=1568
v=1568^1/2

Answer 6

using the kinematics equation the velocity is 19.7m/s

equation, V squared =Vo squared + 2ax

V is velocity
Vo is initial speed
a is acceleration which is gravity
x is distance traveled

Answer 7

In my simple way I get ~64 feet per second. You didn't specify how you want the answer. Since you posed the question in metric, I'll give it in KPH: ~70
In metres per second it is: ~20

Answer 8

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